Train dispatching system for railroads



Sept. 6, 1938. N. D. PRESTON TRAIN DISPATCHING SYSTEM FOR RAILROADS 9 Sheets-Sheet 2 Filed April 4, 1929 m H E Sept. 6, 1938. N. D. PRESTON TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed April 4, 1929 9 Sheets-Sheet 5 JU JU Gm .3 FN 2 .5 EN 2 m 15. a... N: km mm 2 l fiTit y e 93 N aN mg. g l q ha ih-fld 2 a 02m 92 1.1 x A? 211 T1 222 2 I. A-V n r 2 3 3 sag ll m8 m3 as an an H d mwmh A Lure? m3 2 6 v9 F b2 mm as mm m8 u mm 33 m2 2? E km 3m mam? w I 3 m mm 2 E on o g B an ma f u b NNN M 2 am e hm. m M ow Inn 3 13% fi 2 55890 E. in 6 mm M 6 Sept. 6, 1938. N. D. PRESTON I TRAIN DISPATCHING SYSTEM RAILROADS Filed April 4, 1929 9 Sheets-Sheet 4 a aw 6 nd 3 *lL s m r U i 3? ON. 2 \A EY A L HR 3:. Mm 4E WL- mm HE ME. n 53m m N o. u

I Sept. 6, 1938. N. D. PRESTON TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed April 4, 1929 9 Sheets-Sheet 5 Sept. 6, 1938.

N. D. PRESTON TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed April 4, 1929 9 Sheets-Sheet 6 Sept. 6, 1938. N. D. PRESTON TRAIN DISPATCHING SYSTEM FOR RAILROADS 9 Sheets-Sheet 7 Filed April 4, 1929 Sept. 6, 1938; N. D. PRESTON TRAIN DISPATCHI NG SYSTEM FOR RAILRO ADS Filed April 4, 1929 9 Sheets-Sheet 8 EL QL Aw m at. I. w QE 0 Sept 6, 1938. N. D. PRESTON I TRAIN DISPATCHIING SYSTEM FOR RAILROADS Filed April 4, 1929 9 Sheets-Sheet 9 Patented Sept. 6, 1938 PATENT OFFECE TRAIN DISPATCHING SYSTEM FOR RAILROADS Neil D. Preston, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application April 4, 1929, Serial No. 352,558

71 Claims.

This invention relates to dispatching or centralized control systems for enabling an operator or dispatcher to control the movement of switches and signals over an extended territory, subject to the protection of a suitable block signal system, so as to facilitate and expedite train movement, the invention being more particularly directed. to a system of communication to and from the dispatchers office for obtaining the necessary indications and controls.

In a dispatching system, it is essential that the dispatcher or operator be advised of the movement of trains in the territory under his supervision. This may be done by transmitting to the dispatchers oflice an indication, commonly known as an OS indication, when a train passes a known distant point, that is, when a train enters and leaves a track section. Since the movement of trains may be such as to require a transmission of a number of such OS indications at the same time, it is desirable to embody a communication system of the so-called synchronous type as distinctive from a code type.

In the synchronous type communication system, to which the present invention relates, the controls and indications to and from the dispatchers ofiice are transmitted over channel circuits, automatically set up in rapid sequence over a signal or message line and a common wire between the dispatchers office'and several control points along the track, the indications or controls being transmitted sequentially by the energization or de-energization of these channel circuits from sources of current located at the dispatchers ohice or at the distant control points. Such a synchronous type system, using rotary selectors or distributors, is shown and described, for example, in my prior Patent No. 2,082,462 granted June 1, 1937 on an application filed June 16, 1927.

In the synchronous type of communication system, since the channel circuits must be set up one at the time in sequence, with each channel circuit maintained for such time as is required to transmit the desired indication or control, the total time cycle for setting up all of the channel circuits for the dispatchers territory is increased as the system is extended to include more channel circuits for a greater number of controls or indications. Since a given channel circuit is set up only once in this total time cycle, it will be evident that the greater the time of this cycle, the greater is the possible time delay in transmitting a control or indication; and in many instances in the handling of traffic, too great a delay in bta ing a p e to lsv l mQvtm n 9; in

receiving an OS indication seriously handicaps the dispatcher in obtaining eficient and expeditious movements of traific. For these reasons, it is desirable to limit the setting up of the channel circuits of the synchronous type selecting system to those actually required to transmit a new control or indication.

Under ordinary conditions of handling railway trafiic, the dispatcher is frequently able to determine in advance the location in his territory where train movements are likely to occur next which will require him to make a change in the position of switches or indications-of signals; and it is desirable that the dispatcher should be able at will to confine the channel circuit selection to a particular place or part of the territory under his supervision, so as to obtain quick response to lever manipulation and prompt OS indications. In thus restricting the operation of the communication system to a selected portion of his territory, the dispatcher of course for the time. being is out of communication with the rest of the territory; but under the circumstances existing when the dispatcher manually restricts the channel circuit selection to a selected portion of the territory, he will not be interested for the time being in OS indications from the rest of the territory, nor desire to control any switches or signals at other places.

With these and other conditions in mind, it is proposed in accordance with the present invention to provide a communication system of the synchronous type in which communication is established between the dispatchers office and each of several stations or other divisions of the dispatchers territory one at a time in turn by sectionalizing the system into stations or corresponding divisions, and transferring the communication to the dispatchers oflice from section to section in turn. Another feature of the invention is that the channel circuits for these stations or sections are set up only as required to transmit a new indication or control. Also, in accordance with this invention, the system is organized so that the dispatcher, by a simple manual manipulation, may restrict the channel circuit selection to a given selected station at any time and for as long as he desires.

In accordance with this invention, the channel circuit selection at the several way-stations, and also preferably in the dispatchers office, is obtained by groups or series of sequentially operated neutral relays, such neutral relays for channel circuit selection being advantageously employed with sectionalized communication or station se- As illustrative of one specific embodiment v 'of 1: the invention, there is shown on theaccompany-h ing drawings a typical organization of devices and circuits, constituting the equipment for the dispatchers oflice and the way-stations, for the application of the system to a single track railroad; but it should be understood that the system may be employed for the control of switches, signals or other devices, and'for the indication of the operation of such devices or train movements,

in various other ways. The parts and circuits are shown in the drawings diagrammatically, with certain conventional illustrations, more with the object of making it easy to understand the .principles and mode of operation of the system, rather than for the purpose of showing the particular constructions or arrangements preferablyadapted in practice.

In the accompanying drawings, Fig. 1A and Fig. 1B illustrate the equipment in the dispatchers oflice; Fig. 2A shows the equipment at the station A nearest the dispatchers o-ffice; Fig. 2B shows certain parts of another station B and the station Z farthest from the dispatchers ofiice; Fig. 3 shows certain parts and circuits, partly in the dispatchers office and partly at one of the stations, which are involved in auto-- matically starting the system into operation; Fig. 4 shows the line circuits and relays involved in establishing communication with one station at a time, these parts and circuits being shown in the condition which they assume when the system is sectionalized; Fig. 5 illustrates the parts and circuits, partly in the 'dispatchers ofl'ice and partly at a station, which relate to the testing to determine if channel circuits have to be set up for that particular station to transmit a new OS indication or control; and Figs. 6 and 7 show modified forms of the line circuits and relays for sectionalizing the system.

Fig. 1A above Fig. 1B is intended to show the arrangement and organization of the equipment for the dispatchers ofiice; and Figs. 2A and 2B, placed end to end, are intended to show how the system is arranged to include the station equipment. A complete system involves duplication of many of the parts and circuits shown, depending upon the number of stations involved; as will readily be apparent as the description progresses.

Equipment at the dispatchers oflice-At the central control station, conveniently termed the dispatchers ofiice, where the operator or dispatcher is stationed, the equipment comprises in general a suitable track diagram or model board of the track layout of the territory under the supervision of the dispatcher, with small electric lamps or other indicators to register the OS indications; a series of manually operable levers, by means of which the dispatcher is able to control the operation of the switches, signals, and other devices, at

several stations; a plurality of channel selecting devices, one for each station, preferably in the form of a group or bank of neutral relays; a power operated rotary circuit controlling device, conveniently termed astation selector, for establishing the necessary inter-connection between the groups of channel selecting relays, and other devices of the dispatchers office equipment, and for transferring communication from the dispatchers office to each station in turn; an impulse producing means, preferably in the form of relays, for providing the necessary impulses for causing the sequential operation of the groups of channel selecting relays as required; and various other relays and auxiliary circuits for providing automatic starting and stopping of the system, manual station selection, and other functions.

'As' representative of the track diagram, there shownin Fig. 1A 'a'single passing siding S,

with a lamp 6 located near each end to indicate, when lighted, that'there is a train present on the usual short detector track circuit at the cor responding end of the corresponding siding in the Ifield. In practice, this diagram of course comprises a large number of stretches of track, either single or double,,with passing siding, crossovers, and the like, according to the character of the railroad in the territory under the super vision of the dispatcher; and the lamps 6, together with the means for controlling them, are duplicated to provide for the desired OS indications at the various points in the control territory. Similar lamps, when properly controlled over a corresponding channel circuit, may be used to indicate the position of the distant switches or signals, or to communicate to the dispatcher any other desired information.

Each of the OS lamps 6, as shown in Fig. 1A, is controlled by an OS relay 1 of the polar type having a dead-beat armature 8 retained in one or the other extreme position, depending upon the polarity of current last flowing through the winding of this relay. In order that the lamp 6, when first lighted and until recognized by the dispatcher by a manual manipulation, may be readily distinguished from all the other lamps on the track diagram which may be lighted, provision is preferably made so that the lamp 6 is intermittently lighted or flashed, until the dispatcher pushes a button, whereupon the lamp shines steadily with reduced brilliancy, until automatically put out. For this purpose, a cam 9, rotated by a small electric motor 10, or other suitable means, operates a spring contact finger H to intermittently connect one terminal of a source of current, marked to a bus 12. When the OS relay 7 is energized with the correct polarity, assumed to be negative, its contact finger 8 assumes the dotted line position, establishing a circuit from the other terminal of said source, marked over wire l3, through lamp 6, wire M, back contact 15, of the relay l6, and wire I! to the bus l2, so that the lamp 6 is intermittently lighted as the cam 9 rotates and energizes the bus l2. When the dispatcher pushes a button l8, and moves the armature IS in position to be attracted and held by the relay IS, the lamp 6 is energized steadily in series with the relay l6, and with reduced brillancy, due to the additional resistance of the relay IS in the circuit. When the OS relay 1 is operated to return its contact finger 8 to the normal position, the lamp 6 goes out and the relay I 6 is deenergized, permitting its armature I5 to return to the normal position.

As representative of the levers manually operable by the dispatcher, there is shown in Fig. 1A a lever L, arranged to be moved up and down to either of the two extreme positions, this lever 75.

being intended to be used for the control of the power operated switch at the'gendof the siding just above this lever; Another lever LS, movable from an intermediate ormiddle position, as shown, to the right or left, to either of two extreme positions, is intended to be used for controlling the signals at the corresponding end of the distant siding, and selecting the direction in' which trafiic may be permittedto move at that end of the siding. The various levers in the dispatchers office are identified with the corresponding portions of the track diagram by position, number, or the like.

The levers L and LS, and all other levers in the dispatchers office, are each provided with contacts which are normally closed during the movement of such lever from its existing position to some other operated position. In the simple form diagrammatically shown, a switch arm 20 is suitably connected to the lever L so as to move therewith, and engages a contact 2| momentarily as this lever is moved from one extreme position to the other. Similarly, the other lever LS has connected thereto a switch arm 22, arranged to engage contacts 23 momentarily, whenever this lever is shifted from any existing position to another operatedposition.

The levers L and LS are arranged to make and break contacts for the control of their respective devices; and in the diagrammatic ar rangement shown, the lever itself carries insulated contact pieces 24 for connecting contacts indicated as arrows. In the case of the lever LS, which has three operated positions, a cam 25, movable with the lever, is arranged to engage a roller on a spring contact finger 26 and shift it to one position, as shown, when said lever is in its middle position, so as to engage a contact, illustrated as an arrow, and to allow the finger f 26 to move to the other position and engage another cooperating contact, also indicated as an arrow, when said lever is in either of its extreme positions.

Referring to- Fig. 1B, the rotary circuit controller of the station selector SS, in the simplified form shown, comprises a shaft 30, indicated by dot-and-dash lines, which is arranged to be driven by suitable electric motor 3| through a friction clutch32. It is contemplated that the motor 3! is constantly operating, tending to drive the shaft 3!], and that the clutch 32 slips while the shaft 30 is held stationary and the system is at rest. This is merely a typical arrangement, and various other devices may be employed for driving the shaft 30.

The rotation of the shaft 38 is controlled stepby-step by a suitable escapement device, which as. shown comprises an escapement wheel 33, having teeth spaced around its periphery, corresponding to the number of stations of the system. The space between two successive teeth represents a movement of the shaft 30 from one station position to the next, this constituting one full step of the escapement wheel 33. The escapement wheel 33 is advanced one-half step at a time by the operation of suitable detent devices 34 and 35, actuated by stepping magnets 36 and 31 from the spring held engaging position. Upon energization of the stepping magnet 31 and retraction of the detent 35, the shaft 33 may rotate clockwise, in the direction shown by the arrow, one-half step, where it is stopped and held by the other detent 3E; and upon energization of the other stepping magnet 33 and retraction of the other detent 34, the escapement wheel 33 and shaft 30 advance anotherhalf step, making one full complete step.

Fixed to the shaft 30 are contact arms 40, M, 42, 43, and 44, arranged to engage stationary contacts in different positions of the shaft. The full step positions of these arms are shown in dotted lines. These arms are connected to suitable wires, these connections as shown being direct, but in practice being made through suitable slip rings. These arms are of course insulated from each other. Also fixed to the shaft 39 is a cam 45, which is arranged to operate a spring contact finger 46 to open and close a circuit in different positions of the shaft, as hereinafter explained. i

In the dispatchers office, for each station of the system, there is a group of relays and other devices, which are the same for each station, so that a description of one will serve for all. This group of devices for each station comprises a bank of neutral relays for the selection of the channel circuits for the corresponding station. One bank of such relays l, 2, 3, and 4, is shown in Fig. 1B, as representative of the channel circuit selecting relays for station A. There will be as many of these channel circuit selecting relays as required for the number of channel circuits for the corresponding station. Associated with these channel selecting relays for each station is a lever relay LV, a test relay TS, and a manually operable circuit controller K.

The equipment in the dispatchers ofiice also includes a line relay LR, a channel circuit impulse relay CI, with two associated relays 48 and 49; a starting relay ST; and a transfer relay TR, with itsassociated slew pick-up relays 50 and 5|.

The system employs four line wires, comprising a common wire C, a signal or message line SGL, a stepping line STL, and a transfer line TRL, which extend from the dispatchers oflice throughout the territory under the supervision of the dispatcher and are connected to each of the stations in the manner hereinafter explained.

As shown, the system is arranged to be operated by direct current; and for this purpose suitable batteries, motor generators, or other suitable sources of current are employed. One of these sources of current, represented by the bat tery 52 is used for energizing circuits wholly local to the dispatchers office; and for simplicity, the terminals of this source are identified as and and the local circuits are shown as terminating at and The other source of current, represented by the batteries 53 and 5 3, is employed for transmitting direct current of opposite polarities over the line circuits to the various stations; and for this purpose the midpoint of these batteries is connected to the common C, and the other terminal of these batteries, which are of opposite polarity, are identified as (13+) and (B), the wires connected to these terminals being for simplicity marked (3+) or (B).

Station equipment-Fig. 2A shows the station equipment representative or typical of the station at one end of a passing siding PS. Although other track lay-outs, with various arrangements of switches and signals may of course be controlled by a similar station equipment, the equipment for station A, shown in Fig. 2A, is assumed to be adapted to control the operation of a suitable power operated switch machine and the clearing of signals 55, 56, 51, and 51a, subject to track circuit control, and also for transmitting to 7 the dispatchers office an OS indication that the usual detector track circuit at the end of the siding, provided with a track relay T, is occupied by a train. The operation of the switch machine (not shown) is intended to be controlled to the normal or reverse position by a dead-beat polar relay 58, with suitable provisions for approach and detector locking. The clearing of the signals 55, 56, 51 and 51 subject to track circuit control and the position of the switch, is determined by the position of the dead-beat armature of. the polar relay 59, the clearing of the particular signals for opposite directions of traiiic being determined by the position'of the dead-beat armature of the polar relay 60. These relays 58, 59 and 89 are controlled over channel circuits from the dispatchers ofiice, as hereinafter explained. The way in which these relays control the operation of the switch machine and signals may take various forms, such as shown, for example, in my prior application, Ser. No. 199,325, filed June 16,

, 1927, nowv Patent No. 2,082,462 granted June 1,

1937 or in the application of S. N. Wight, Ser. No. 321,185,filed November 22, 1928, now matured into Patent No. 1,889,457 granted November 29,

The track relay T controls two neutral. relays 62 and 63, which are arranged to store up the indication of the occupied or unoccupied condition of the detector track circuit, until such indication has been transmitted to the dispatchers office, in a manner more easily explained in connection with the description of the operation.

- At each station is a bank of neutral channel circuit selecting relays, corresponding in number to those in the dispatchers ofiice. The channel circuit selecting relays: for station A in Fig. 2A are designated l 2 3 and 4 and correspond with relays I to 4 inclusive shown in Fig. 1B. These two banks of relays, one in the dispatchers oilice, and one at the corresponding station, are operated synchronously and sequentially by impulses on the stepping line STL, to establish in rapid sequence the channel circuits required to transmit the desired control or OS indications for station A. These channel circuit selecting relays at each station (see Fig. 2A) are controlled by a line relay, as LR for station A, of the polar type, having its armature or contact fingers biased to the middle or neutral position. The line relay LR in the dispatchers ofiice is of the same type.

Also located at each station is a polar transfer relay TR, having a dead-beat armature remaining in the position it was last put; a transfer stick relay TRS, of the neutral type having two windings; and a double-wound slow release relay SL.

At each station is a suitable source of current for energizing local circuits, and another source for imposing difierent polarities of currents between the signal line SGL and the common Wire C. These sources of current are preferably storage batteries, maintained trickle charged in a suitable way, and are shown the same as for the dispatchers oflice as batteries 52, 53, and 54, with the same symbols for their terminals and connection to the common wire C.

Operation The parts are shown in Figs. 1A, 1B, 2A, and 2B, in the normal or inactive position, with the system at rest, ready to be automatically started whenever it becomes necessary to transmit a control or indication.

In this normal condition shown, in the dispatchers oflice (see Fig. 1B), the starting relay ST, the transfer relay TR and the associated relays 59 and 5|, the channel impulse relay CI andassociated relays 48 and 49, and the stepping magnets 36 and 31, are all de-energized. The channel circuit selecting relays, as l, 2, 3, and 4, the lever relays LV and the test relay TS, for each of the stations, are also de-energized. The line relay LR in the dispatchers ofiice is also de-energized.

At each of the stations (see Figs. 2A and 2B), the transfer relay TR is de-energized, but its contact fingers are held to the right, in the positionto which they were last operated by a positive impulse. The transfer stick relay TRS is also de-energized. The slow release relay SL is maintained energized by a stick circuit from through its front contact 66, wire 61, its lower winding, wire 68, through back contact 69 of the relay TRS, to negative The transfer line TRL is completed through all the stations to the last station Z through the back contacts H of the several transfer stick relays TRS. The stepping line STL is also completed through all of the stations, up the last station, through the back contacts 12 of the several transfer stick relays TRS. As the last station Z (see Fig. 2B) the transfer line TRL is connected to common C. The stepping line STL is open circuited at the last station.

The several transfer relays at the several stations are connected in multiple between the transfer line TRL and common C through the upper winding of the slow relay SL, this connection being traced (see Fig. 2A) as follows:from the transfer line TRL, wire 13, relay TR wire 14 and 15, upper winding of relay SL, wire 16, back contact 18 of the relay TRS, to C.

Starting.-The system is arranged so that it is automatically set into operation either by the movement of any lever in the dispatchers office to a new operated position, or by the entering or leaving of a train at any one of the detector track circuits so as to cause a change in the position of the corresponding track relay T. In other words, whenever a new control or OS indication is to be transmitted, the system is automatically set into operation.

Considering first how the system is automatically started upon a new lever movement, when any lever in the dispatchers ofiice is manually moved to a new operated position, the contacts associated with that lever, such as 292l and 22-23 (Fig. 1A), are momentarily closed to energize the corresponding lever relay LV. If the lever L, for example, is the one which is moved from the upper position shown tothe lower position, the closing of the contacts Zli-Zl during this movement establishes a circuit from positive through contacts 20--2l, wires l8, l9, and 89, relay LV to negative The relay LV, when thus energized momentarily, is maintained energized by a stick circuit from negative through LV, wires 80 and BI, front contact 82 of the relay LV, wire 83, back contact 84 of the relay l, wire 85, back contact 86 of relay 2 to positive This stick circuit is also established through the front contacts 84 and 86 of the relays I and 2 and the wire 81, for reasons hereinafter explained.

Whenever any relay LV is energized, the closing of its front contact 88 connects positive over wire 89 to the starting bus 90, which is connected by wire 9| to the lower winding of the starting relay ST to negative Thus,

when any lever is operated to a new position, the starting relay ST is energized, and is maintained energized by a stick circuit from negative through the lower winding of the relay ST, wires 9| and 92, front contact 93 of the relay ST, wire 94, and contact finger 46, operated by the cam 45, to i The starting relay ST may also be energized to start the system into operation whenever any track relay changes to a different position, Referring to Fig. 2A, assume that the track relay T is de-energized, by the entrance of a train into a corresponding detector track circuit. The dropping of the track relay T energizes the relay 62, over a circuit readily traced on the drawings; and. as the relay 62 attracts its armature, its make-before-break contacts 95 momentarily close and establish a pick-up circuit for the relay 63. The relay 62, when picked up, is stuck up through its front contact 96 and the front contact 97 of the relay 63. The relay 63, when picked up, is stuck up through a stick circuit from negative relay 53, wire 98 and'99, front contact I99 of relay 63, wires IOI and I32, back contact I33 of the channel circuit selecting relay 3 to A stick circuit for the relay B3 may also be established over wire IM and front contact I35 of the channel circuit selecting relay 4 for reasons hereinafter explained.

The energization of the relay 63 in this way closes its front contact I86 and establishes an energizing circuit for the upper winding of the starting relay, which may be traced as follows (see Fig. 2A) :--starting at C, front contact I06, of relay 63, wire I01, front contact I08 of the relay SL, wire I09, contact Ili! of the transfer relay TR in its right or positive impulse position, wire III and H2 to thesignal lineSGL, thence to the dispatchers office through arm 4|, wire H3, upper winding of the starting relay ST to (3+). There is a similar starting circuit for each station, which is closed if the relay 63 at that station is-energized. The two windings of the starting relay ST are, of course, so arranged as to act cumulatively if both should happen to be energized at the same time. i

A starting circuit is established the same way at any station, when the system is at rest, if the track relay T at that station should happen to pick up, due to movement of a train out of the corresponding detector track circuit. Assuming that the OS indication of occupancy of the detector track circuit has been transmitted, as hereinafter explained, so that the relay 63 has been de-energized, the relay 62 is maintained energized only by its pick-up circuit, while the track relay T de-energized; and the relay 62 is at once ole-energized when the train leaves the detector track section and the track relay T picks up to open its back contact. Upon such de-energization of the relay 62, its make-beforebreak contacts 95 momentarily close to energize the relay 63, which is stuck up as already described, and establishes the starting circuit through its front contact I06, as just explained.

Inthis way, whenever there is any, change in track circuit conditions, or any lever movement, the starting relay ST is energized and the system set into operation.

Sectionalizing.The first step in the operation is to sectionalize the system, so to speak, so that communication is established between the dispatchers office and the first station A. As above pointed out, in the normal condition of thesystem when at rest, both the transfer line TRL andstepping line STL are completed through the several stations, and the first step in the operation is to break up or sectionalize the transfer line TRL and the stepping line STL, so that they go only as far as the first station A.

Upon energization of the starting relay ST, and theclosing of its front contact II4, a circuit is established for energizing the stepping magnet 31 (see Fig. 1B) from through arm 4-0, wire H 5, front contact II4 of the relay ST, wires H6 and H1, stepping magnet 31 to This releases the escapement wheel 33, and allows the shaft 33 to turn clockwise, in the direction indicated by the arrow, one-half step, where the switch arms GE -M occupy the position midway between the initial position and the first dotted line position. In this half-step position, a negative impulse is applied to the transfer line TRL from (B) over arm 44, wire F8, relay TB in the tower, and wire II9 to the transfer line TRL, and thence along this transfer line through the several transfer relays TR at the various stations in multiple. This negative impulse through the transfer relays TR causes the relays TR, TRS and SL to assume the positions shown in Fig. 4.

Referring to Fig. 4, the contact fingers of thetransfer relays TR are all in the left hand or negative impulse position. In this position a local circuit is established from through the contact finger I20 of the relay TR to the left, wire I2I, upper windingof the transfer stick relay TRS to negative This energizes the relay TBS which interrupts the stepping line circuitSTL at its contact 12 and the transfer line circuit 'I'RL at its contact II. The opening of the back contact 69 of the relay TRS also breaks the stick circuit for the relay SL, which is de-energized, since its pick-up circuit is broken at the backcontact 10 of the relay TRS. In this l connection, it should be noted that the relays TRS are made sufliciently slow in picking up that each of the transfer relays TR will be energized long enough to shift their contact fingers before the transfer line TRL is broken up by the opening of the back contacts II of the relays TRS.

At the first station A, nearest to the dispatchers oflice, the stepping line STL is connected to the line relay LR at that station through the front contact 12 of the relay TRS and wire I22 to common C, so that the line relay LR; in thedispatchers ofiice, and the line relay LR? at station A are connected in series over the stepping line STL and common. With this stepping circuit for station A completed, through the energization of the relay TRS at that station, the stepping line circuit is energized with a negative impulse to shift contact fingers of the ,two line relays to ,the left hand position, this negative impulse being applied to the stepping line STL (see Fig. 1B) from (3-) through back contact I23 of the relay 49, wire I24, relay LR, and wire I25 to thestepping line STL. The reason for this negative impulse will be explained later. i I

After this operation of sectionalizing has been completed, the slow pick-up relay 59, which has been energized (due to the movement of the contact fingerIZB -of the relay TB in the dispatchers ofiice to the left) closes its front contact I21 and applied positive over wire I28 to the bus I29 connected by wire I30 to the stepping'magnet 36. The energization of the stepping magnet 36 allows the escapement wheel 33 pleting the first full step in the operation.

In this first full step position of the shaft 30, the stepping magnet 31 is again energized through arm 46 and contact I3I, wire I32, and over wire I I5 through the front contact .I I4 of the starting relay, etc., as hereinbefore pointed out. This energization, of the stepping, magnet 31 advances the shaft 30 another one half-step, bringing the parts-into the position shown in Fig. 5, which corresponds to the position for testing or determining whether or. not channel circuits shall be set up for the first-station A. In this position, the cam 45 has disengaged the finger 46, breaking the stick circuit for the starting relay ST; .but therelay ST does not release its armature unless all of, the relays LV are then deenergized, which occurs at some subsequent point in the operation of the cycle of the system when all 'of the channel circuits have been cleared out, as hereinafter explained.

Test for channel circuit selection-For reasonsflto be explained presently, it is desirable to determine automatically; upon selecting each station, whether or. not there is any new control or indication to be transmittedfor that station, and thengo through, the operation of setting up the;channel circuits only'if such new control or indication is to be transmitted. For this purpose, a circuit, conveniently termed a test circuit, is established between the dispatchers ofiice and each stationinturn as it is selected, and through; the medium, of this circuit, together with the condition .of the corresponding lever relay LV, it'isaautomaticallydetermined whether or not the individual channel circuits for that station shall be set up.

To-explain this feature of the operation, assume-that, since :the system last operated and cleared out all (of; the channel circuits, either alever for station:A wastop'erated to a new position, or that the ,track relay T at station Aihad picked up or dropped. In eitherof these cases, ,therewould be anew control or OS indication to be transmitted, and the individual channel circuits at station A should be set up.

. .Consider first that a lever, such asL, for station A was operated to a new position. This energizes the relay 'LV for that'station'. Then, ,as soon-as :the shaft 30 of thestation selector assumes the half-step position, shown in Fig. 5, a test channel circuit through the test relay TS in the dispatchers oflice for station A is established as followsrstarting at C, relay TS, wire I35, back contact I36, of channel circuit selecting relay I, wire I31, back contact I38 of relay 2, wire I39, back contact I48 of relay 3, wire I4I, back contact I42 of relay 4, wire I43, arm M on the shaft 30, to the signal line SGL, thence to station A, wires H2 and -I44,'finger I45 of the relay LR? to the left, wire I46, back contact I42 of channel circuit selecting relay 4, wire I4I back contact I4Il of relay 3%, wire I39 back contact I38 of."rel'ay '2, wire I31, back contact I36 of relay I wire I41, and contact finger I48 of the relay 63 to 3+ or 3-, ac-

cording to theposition of this finger, and thence back to common.

The contactfinger of the relay LR is in the left or negative impulse position to complete the circuit just traced, since the stepping line circuit STL is energized negatively, as above explained. V '7 I 'On the assumption that alever for station A had been operated to energize the relay LV, but

' wires I68 and lays 48 and 49 continues and applies and shaft 30 to make another half-step, comthere had been no change in the track relay T at station A, the finger I48 of the relay 63 is in the lower pos ition, energizing the relay TS over the test channel circuit just traced negatively to move the contact finger -I 58 of the relay TS to the left, whereupon with the lever relay LV energized, a circuit is established for energizing the channel impulse relay CI as follows:starting at negative relay CI, wire I5I to bus I52, wires I53 and I54, front contact I55 of the relay LV, wire I56, finger I59 of relay TS to the left, wires I51 and I58, arm 40 in the half-step position (see Fig. 5) to positive If it shoul'd'happen that there had been a change in the condition of the track relay T at station A, subsequent to the last clearing out of the channel circuits at station A, then the finger I48 of the relay 63 would be in the upper position, energizing the relay TS positively, and thereby energizing the relay CI directly over wire I59, independently of the position of the contact I55 of the relay LV.

Thus, whether there is a new lever operation, or a change in the condition of the track relay T, for station A, the channel impulse relay CI is energized. This relay CI, when energized, maintained energized by a stick circuit individual to each station, which may be traced from negative relay CI, wires I5I, I60, front contact I6I of relay CI, to bus I62, thence over wire I63, back contact I64 of the channel circuit selecting relay 4, wires I65 and I66, contact finger I61 of the circuit controller K in the normal position, I58, and arm 46 to positive In this way, the relay CI is maintained energized until the last channel circuit selecting relay, which as shown is relay 4', is energized, or in other words until the necessary number of stepping impulses have been applied to the stepping lineSTL to operate all of the channel circuit selecting relays.

Any suitable means may be employed to apply positive and negative impulses to the stepping line STL, upon energization of the. relay CI. As shown, the energization of the relay CI and the closing of its front contact I16 energizes the relay 48 through the back contact I1I acting relay 49, and the closing of the front contact I12 of the relay 48 energizes'the slow acting relay 49. After a time, sufficient for the slow acting relay 49 to attract its armature, its contact finger I23 is raised to the upper position, applying a positive impulse to the stepping line STL through the line relay LR in the dispatchers ofiice and through the line relay LR. at station A, or such other station as may then be selected. As soon as the armature of the slow acting relay 49 is attracted, the contact finger I1I de-energizes the relay 48, which in turn opens its front contact I12 and de-energizes the relay 49. After an interval of time required for the relay 49 to retract its armature, its finger I23 drops and applies a negative impulse. This same operation of picking up and drop-ping of the re- 7 alternate positive and negative impulses to the stepping line STL, until the relay CI is de-energized, whereupon the relay 48 can not again pick up upon dropping of the relay 49.

Channel circuit selection-The alternate positive and negative impulses impressed upon the stepping line STL cause the contact fingers II5 of the line relay LR in the dispatchers ofiice, Fig. '1B,and the contact fingers I16 of the line relay at the station then in communication with of the slow station A and thence to 4 direct to negative the dispatchers oifice, as the line relay LR for station A, to shift back and forth'from one extreme position to the other,-the position to the right being, for convenience, assumedto correspond with a positive impulse. These two contact fingers H5 and I16 of these two line relays are thus operated synchronously, since the relays are connected in series in the stepping line circuit, and have the current built up in their windings at the same rate, irrespective of the length of the line circuit.

The movement of these contact fingers H5 and HE back and forth is used to energize sequentially the relays I-4 and I -4 which operate their corresponding contact fingers simultaneously and synchronously, so as to set up in rapid sequence a series of channel circuits for the transmission of the desired controls and indications. The control circuits for these channel selecting relays I-4 and l -4 are the same, and a description of these circuits for the relays I-4 in the dispatchers ofiice will be sufficient.

Back and forth movement of the contact fingers II5 of the relay LR alternately connects to the two bus wires a and b. A positive impulse on the stepping line circuit energizes the bus a, and negative the bus b. The first impulse on the stepping line circuit, upon energization of the channel impulse relay CI is positive, due to the energization of the relay 49. This first positive impulse energizes the upper winding of the relay I over a circuit which may be traced from bus a, wire I8I, upper winding of relay I, wires I82; I83, I84 and I85, back contact I86 of the relay 4, wire I81, to arm 42 of the station selector shaft 39 inthe position corresponding to Although the bus at is connected to the upper windings of therelays I of the other groups of channel selecting relays for the other stations, the relay l for station A is the only one which is energized because the energizing circuit for theother relays I is broken at the arm 42.

The relay I, when thus energized by the first positive impulse on the stepping line circuit, is

maintained energized by a stick circuit through its lower winding from through its front contact I88, wire I89, lower winding of relay I, wire I98, to wire I83, and thenceto along the same path through the back contact I86 of relay 4 above traced.

On the next negative impulse, the bush is energized, and this energizes the upper winding of the relay 2 over wire I9I ,-front contact I92 of relay I, wireI98, upper Winding of relay 2, and wires I94 and I95 to wire I84 and thence to over the same path above traced. The relay 2, when thus energized, is stuck up through its front contact I96 the same as the relay I.

The next positive impulse, energizing bus (1, energizes the upper winding of the relay 3 over wire I91, front contact I98 of relay 2, wire I99, upper winding of relay 3, and wires 209 and 2M to the wire I85 and thence to The relay 3 is similarly stuck up through its front contact 292.

Upon the next negative impulse, energizing the bus 11, the relay 4 is energized over wire 203, front contact 294 of relay 3, wires-285 and 206, relay The relay 4 is stuck up through a circuit which may be traced from negative through relay 4, wires 296 and 20?,

front contact 298 of relay 4, wires 209 and I66, contact finger 1 I61 of switch K in the normal closed position, wires I68 and I58 to arm 40, in the station A position, to plus (-1-).

circuit, and that the relay tion of switches or signals, .informationmay be transmitted from a station Upon energization of the. relay 4, the opening of its back contact I86 de-energizes the relays I, 2 and 3. The energization of the relay 4 also breaks at its back contact. I64 the stick circuit for the channel impulse relay CI, so that the impulses on the stepping line cease.

In this way, the channel circuit selecting relays I-4 are energized sequentially one at a time. The same operation of the relays I -4 at station A takes place, except that the relay 4 at the station is stuck up through its front contact 288, Wire 2| I, through the contact fingers 2I2 of the transfer relay TR, which is then in its negative or dotted line position as shown in Fig. 4, as a result of the sectionalizing negative impulse, as hereinbefcre explained.

It should be understood that any desired number of channel circuit selecting relays may be employed by extending or duplicating the control circuits as shown for the relays I--4, the last relay of the series being stuck up in the same way as the relay 4. The number of relays required would depend upon the number of channel circuits required for the corresponding station.

Any desired control or indication may be transmitted over any one of the several channel circuits set up by the channel circuit selecting relays. These channel circuits may be energized with alternating current or direct current of different polarities from sources either in the dispatchers office or at the station. As shown, the channel circuits are employed to transmit positive or negative direct current impulses to operate dead-beat polar relays, but obviously other arrangements could be employed.

I As typical of a channel circuit for transmitting an indication from the station to the dispatchers office, assume that the track relay T at station A (seeFig. 2A), is tie-energized by the presence of the train on the corresponding detector track 62 is also energized. Then, when the channel circuit selecting relays i and I are energized by the first positive impulse, a channel circuit for energizing the OS relay I for station A in the dispatchers office is established and may be traced as fol1ows:-starting at B+, front contact 2I4 of relay 62 (see Fig. 2A), wire ZIB, front contact I36 of the relay I wire 131 back contact I38 '0f relay 2 wire I39 back contact I40 of relay '3, wire I4Ie, back contact I42 of relay 4*, wire I46, contact finger I45 of relay LRA, now to the right (positive impulse position), wires 2I6 and H2 to the signal line SGL thence to the dispatchers ofiice (see Fig. 1B), to arm M of the station selector shaft 39, inits. position corresponding to station A, wire I43, back contact I42 of relay 4, wire I4I, back contact I49 of relay 3, wire I39, back contact I38 of relay 2, wire I31, front contact I36 of relay I (now energized), wire 2|! (Fig. 1B) to Wire 2 I'I of Fig. 1A, OS relay 1 to the common wire C, and thence back to the neutral terminal of batteries 2A). this OS channel circuit,

53 at station A (see Fig.

Current flowing over being of positive polarity, due to the energization of the relay 62, shiftsthe contact finger 8 of the OS relay 1 to the dotted line position, energizing the OS lamp 6 intermittently in the manner previously explained, until this indication is recognized by the dispatcher and button I8 is operated to cause the lamp to burn steadily with reduced brilliancy.

The condition of other track circuits, the posior any other desired the contact fingers .patchers ofiice closes its front contact to the dispatchers office in channel circuit.

As typical ofthe operation of transmitting a control from the dispatchers ofiice to station A, assume that the lever L (see Fig. 1A) is operated to the other position. Then,; upon energization of the channel circuit selecting'relays 2 and 2 a channel circuit, similar to the one above traced, is set up from (3-) over wires 2I8 and 2| 9 (see Fig. 1A) to the front contact I 38 of the relay 2, thence through the back contactsl ltl and I42 of the relays 3 and 4 to the signal wire, to station A through the contact fingers I45 of the line relay LR (now in the left or' negative position), through the back contacts I42 and l I of the relays I and 3 through. the front contact I 38 of relay 2 wire 229 to the polar relay 58 and thence to C. This channel circuit being energized negatively, causes the contact finger of the relay 58 to be shifted to the other position, and in turn operating the switch machine (not shown) to'the other position.

In a similar way, the relays 59' and 60 at station A, (see Fig. 2A), may be operated to one position or the other by the movement of the lever LS (see Fig. 1A), so as to permit one of the signals 55-5! to clear, subject to the presence of trains ahead, dependent upon the position of the switch and the direction of traffic set up by the extreme position to which the lever LS is shifted. Any desired number of switches, signals, derails, or other trafi'ic controlling devices may be controlled by the dispatcher at any given station in a' similar way.

Transfer to the neat station.-After the channel circuits have been setup for station A, as just explained, and upon energization of the last relay, as 4, of the group or'bank of channel circuit selecting relays for station A, current is applied through the front contact I64 of relay 4 over wire 2| 0 to the bus I 29, so as to energize the stepping magnet 36and cause the station selector shaft 30 to advance another half-step to the position where the arms 50, 4|, 4'2 and 43 break contact, and the arm 44 makes contact.

Under these conditions, a positive impulse from B+ is transmitted over arm 44, wire I18 through the transfer relay TR; in the dispatchers oifice and through the'transfer' relay TR at station A (see Fig. 2A). This positiveimpulse shifts I20, 2-I2 and llfiofthe transfer relay TR from the left hand position shown in Fig. 4 to the right hand position shown in Fig. 2A. This movementof the contact finger I20 breaks the energizingcircuit for the upper winding of the transfer stick relay TBS, but so long as this positive impulse exists, the contact fingers of this transfer relay TRS are held in the raised or attracted position by the flow of current over wires I4 and 22I, through the lower winding of this relay TRS, wire 222, and through its front contact 'II] to C. After a time interval, sufiicient for proper response of the transfer relay TR at station A, slow acting relay in the dis- 223 and energizesthe stepping magnet 37, thereby advancing the shaft3Il a half-step, so as to break contact at the arm ,and bring. the other arms 40, II, 42 and 43 into their contacting position for the next station'B.

When the arm 44 breaks its: contact, the positive impulse on the transfer line TRL ceases, and the transfer stickrelay TRS at station A (Fig. 2A) releases its armature and allows its contact fingers to drop; The contact finger of this a similar way over a relay TRS' completes the transfer line circuit TRL over to station'B, and thecontact finger I2 connects the stepping line circuit STL to the line relay LR at station B.

Communication is now established between the 'dispatchers ofiice and the next station B; and as soon as the step-ping line circuit, including the line relay LR in the dispatchers ofiice and the line relay LR in station B, is established, the negative impulse on this line circuit, supplied through the back contact I 23 of the relay 49 causes the contact fingers of these two line relays to assume the left hand or negative position, whereupon a test circuit, similar to the one hereinbefore traced for station A, is set up. If the relay 63 at station Bis energized, due to the picking up or dropping of the track relay T at station B since the last 0g; indication was transmitted, then the test relay TS in the dispatchers ofiice for station B is energized to shift the contact fingers I59 to the right, so as to energize the channel circuit impulse relay CI. Or, if any lever for station B has been operated toa new position, since the last clearing out of the control channel circuits, the relay LV for station B is energized. In this case, the channel circuit impulserelay CI is also energized. Thus, if there is a new control or OS indication for station B to be transmitted, then the energization of the relay CI applies alternate positive and negative impulses to the stepping line circuit and operates the channel circuit selecting relays, such as I--4, at stations B and at the dispatchers ofiice, so as to set up a series of channel circuits for transmitting such new indication or control.

Skipping stations-If it should happen that there has been no change in the position of the levers for station B, and no change in the condition of the track relay T at station B, then the test relay TS for station B in the dispatch-ers ofiice is energized with a negative impulse and its contact finger I50 assumes the left hand position, and also the relay LV in the dispatchers office for station B is de-energized, so that current is supplied to the stepping magnet 36 over wire 224 to advance the shaft 30 another half-step, without time being taken to set up the individual channel circuits for station B. This applies to all of the other stations in the same way.

This automatic holding; or skipping of stations is an important feature of the invention. In the first place, the channel circuit selecting-devices are not operated, unless required for the transmission of new indications or controls so that unnecessary wear on the parts is avoided. Furthermore, the time required-to set up the channel circuits, not needed to transmit a new control or indication, is avoided, so that the total time cycle for scanning, so to speak, the whole controlled territory is greatly reduced, and makes it possible to have a greater number of channel circuits on a single set of line wires, or increase the time for setting up each channel circuit, without obtaining objectionable or prohibitive delay in the transmission of controls or OS indications.

To appreciate thesignificance of this feature of the invention, it should 'be understood that, under normal operating conditions and for such density of trafiic and'train movementordinarily encountered in practice; particularly over an extended territoryof a single trackrialroad, it is very rare that, within a given period of a few seconds, there would be any new ;control or OS indication to be transmitted from more than about one station out of eightor; ten. For example, in an installation for twenty passing sidings, under What can be termed normal or average operating conditions, it is rare that trains would happen to enter or leave track sections at the ends of more than two of these passing sidings exactly simultaneously, or within a limited period of a few seconds, or that the dispatcher will find it necessary to operate a switch or sig-, nal, within the same given period, at more than one or two siding ends. In other words, out of all of the channel circuits for the control territory under the supervision of the dispatcher, during a given period, it may be fairly assumed that, most of the timeat least, only some ten per cent of the total channel circuits are actually required for the transmission of a new control or indication; and by eliminating the time required to set up the channel circuits not needed, it will be evident that the efficiency of the communication system is greatly increased.

This may perhaps be made clearer by a specific example. Assume, for instance, a single track installation of twenty passing sidings, with a station at each siding end, or a total of. forty stations. It is found that it takes about one fifteenth of a second to set up and utilize a channel circuit. The transfer from station to station may be made effectively in about the same time. It would require, therefore, let us say, about one-eighth of a second to select the station and set up the test circuit, making a total time of about five seconds to select and test out all of the forty stations. Assuming each siding end or station requires four channel circuits, if the channel circuits for only ten per cent of the stations have to be set up, then the additional .time for channel circuit selection is about one second, making the total time cycle something in the order of six seconds. On the other hand, on the same assumption of four channel circuits per station, forty circuits per station and a fifteenth of a second for each channel circuit, the additional time required, if. all of the channel circuits were set up, would be over ten seconds, making the total time cycle a matter of fifteenor more seconds. Thus, it might happen that, after a lever had been moved, or a track relay had changed, there would be a delay of some fifteen seconds before there would be any response in the field to such lever movement or indication in the dispatchers office of change in track circuit conditions. In many cases, such a delay would very seriously handicap a dispatcher and interfere with the expeditious and efficient movement of trains. This would be particularly true in the case of a non-stop meet, or similar traffic congestion at a particular point or zone.

Completing station selection.-The same steps of transferring from station to station, establishing the test circuit, and setting up the individual channel circuits for such stations as may be required, as above explained, continues until the last station Z (see Fig. 2B) is reached. After the setting up of the individual channel circuits at this last station Z, or after response of the test relay TS for that station, indicating no need for the individual channel circuits, the stepping magnet 31 is energized in the same way previously explained, to advance the shaft 30 from the position corresponding to station Z one half-step, bringing the arm 43 into the position, one-half step short of. its initial position, and establishing a circuit over wires 226 and 221 to energize the transfer line TRL and the relays TR at the several stations, without energizing the relay TR in the dispatchers olfice. Also, the arm 42 in this last half-step position establishes a circuit to energize the slow pick-up relay 230, which closes its front contact 23l after a time and energizes the bus I129 for the stepping magnet 36, so that the shaft 35) completes its last half-step and reaches its initial position shown in Fig. 1B. The time required for the relay 230 to close its front contact 215i is so selected that the shaft 30 rem 'ns in this last half-step position, and the transfer relays TR. at the several stations are maintained energized positively, for a period of time long enough to cause the slow relay SL in the several stations to pick up their armatures. These slow relays SL, when thus picked up, are stuck up through their front contact 66, wire 61, lower winding, wire 68, and back contact 69 of the corresponding relay TBS, as shown in Fig. 2A.

Thus, at the end of each revolution of the shaft 30, a long positive impulse is applied to the trans fer line TRL to pick up the slow relay SL at the several stations. With the slow relay SL at each station energized, and the contact I I of the relay TR at that station in the right or positive impulse position, the circuit at that station for starting the system into operation is made up, so that when the relay 63 at that station is energized, the upper winding of the starting relay ST in the dispatchers ofiice is energized. The branch circuit at each station for starting the system into operation is broken at once at the contact ill! of the relay TR by the negative sectionalizing impulse on the transfer line TRL, and is maintained broken at the front contact I08 of the relay SL at that station, until the next long positive impulse is transmitted at the end of the revolution of the shaft 30. In this connection it should be understood that the positive impulses applied to the transfer line TRL over arm 44 to transfer a communication from station to station, are not long enough to energize the slow relays SL at the several stations.

After the shaft 30 assumes its initial position, as just explained, the system is ready for another operation. The transfer line TRL is com-- pleted through the several stations, so that when the starting relay is energized and the shaft 30 advances one-half step, the first negative impulse on the transfer line TRL sectionalizes the system, as hereinbefore explained, and at the same time de-energizes the slow relays SL at the several stations to open the starting circuits at all of the stations.

When the shaft 30 of the station selector reaches its initial position after a revolution, it may stay there until the system is set into operation at some subsequent time, or another revolution of the shaft 30 may be at once started, in a manner which will now be explained.

Clearing out of the channel circuits.It will be evident that, during this cycle of operation of thesystem, while communication was set up between the dispatchers office and some intermediatestation, a lever might be operated, or a track relay dropped, at some one or more of the stations which had already been selected and at which the individual channel circuits might have been set up. Consequently, if the system should stop at the end of this first cycle or revolution of the station selector, there could be some control or indication which had not been transmitted, and would not be transmitted until the system was again set into operation by some new lever movement or change of a track relay.

For these reasons, it is important to organize the system so that, when once set into operation, it continues in operation until all of the controls or indications have been cleared out, so to speak. There are several possible contingencies or cases to be considered in this connection.

Assume first that, after the system had passed on to an intermediate station, say station B, a lever is operated for some preceding station, say station A, or the track relay T at some preceding station, as station A, has either dropped or picked up due to a train movement occurring subsequent to the selection of that station. When such a new lever movement for station A occurred, the relay LV for that station was energized, and stuck up through its stick circuit. In the case of a change in the track relay T at station A (see Fig. 2A), the relay 63 would be energized through the make-before-break contact 95 of the relay 62, whether that relay was energized or deenergized by the change in the track relay T; and the relay 63 will be stuck up through the back contact I03 of the relay 3.

When the system completed its cycle of operation under consideration, and the shaft 30 assumes its initial position shown in Fig. 1B, the starting relay ST would be energized in either case, in the same way as hereinbefore explained in connection with the starting of the system from rest, Consequently, another revolution of the shaft 30 would occur. In this way, the shaft 30 continues to rotate until, upon reaching its initial position, all of the lever relays LV are deenergized, indicating that no lever has been operated since the transmission of controls had been completed, and until the relays 63 at all of the stations are de-energized, indicating that no change in track circuit conditions has taken place since the OS indications were last transmitted.

Another contingency is that a lever may be operated for a station while the channel circuit selecting relays are operating, and subsequent to the setting up of the channel circuit for that particular lever. To illustrate, referring to Figs. 1A and 1B, suppose that, after the relay 3 has operated, to break at its back contact M the channel circuit over wire 2I9 to the lever L, this lever is shifted to a new position. It will be evident, that in such a case, it would be necessary to set up again the channel circuits for station A, in order to transmit the new control. For this reason the stick circuit for the lever relay LV is so organized that it is broken, to permit cle-energization of the relay LV, at the back contact 84 of the relay I, when that relay is energized, and before the relay 2 is energized. As soon as the relay 2 is energized, then the stick circuit for the relay LV is completed through the front contacts 84 and 86 of the two relays I and 2, with the result that the movement of any lever thereafter would be registered, so to speak, by the energization of the relay LV. The relay LV is made slightly slow releasing, so that if energized, with the I and 2 up, it does not drop during the momentary opening of its stick circuit upon simultaneous dropping of the contact fingers 84 and 86 of the relays l and 2, which occurs when the relay 4 picks up. Since the energization of the relay LV, as above explained, assures another revolution of the station selector shaft 30, the channel circuits for the station A under consideration are again set up, and the control corresponding to the operation of the lever L under consideration is transmitted in the regular way.

A similar contingency may arise in connection with the dropping or picking up of the track relay T at a station. Considering station A, Fig. 2A, the track relay T may happen to pick up or drop, depending upon the movement of the trains into and out of the corresponding detector track circuits, at any time in the operation of the channel circuit selecting relays I 4 The OS channel circuit is established through the front contact I315 of relay l and is broken through the back contact I38 of relay 2 Since the OS indication can not be transmitted except while this OS channel circuit is set up, and since the train may enter or leave the detector track circuit at any time, it is necessary to make special provisions to assure the transmission of the OS indication.

For one thing, the train may enter the track circuit and drop the track relay T, and again leave the track circuit and permit the track relay T to pick up, before the OS channel circuit is set up, as for instance, while the system is operating at some other station or stations. This condition is likely to happen with short fast moving trains or single locomotives or motor vehicles.

For this reason, provision is made by means of the relays I52 and 63 to store up, so to speak, the OS indication that the track relay T has dropped, until such indication is actually transmitted to the dispatchers office. When the track relay T drops, the relays 52 and 63 are picked up and stuck up in the manner previously explained, and remain stuck up even after the train leaves the track section and the track relay T picks up. With the relay 63 energized, the closing of its front contact let assures starting of the system, if at rest, or another revolution of the station selector shaft 30, if the system is operating. Also, the closing of the front contact I48 of the relay 63 assures that a positive impulse will be transmitted over the test circuit to assure that the individual channel circuits will be set up for the station in question when next selected, so as to transmit an OS indication. Upon operation of the channel circuit selecting relays at the station in question, when the relay 3 picks up, it breaks at its back contact I03 the stick circuit for the relay 63, which releases its armature. As soon as the relay t picks up, the stick circuit for the relay 63 is again established over another branch through the front contact I05 of the relay 4 When the relay 83 drops, it breaks at its front contact 9'! the stick circuit for the relay 62, and

if the trainhas left, the relay 62 is de-energized.

This relay 62, however, is made slightly slow acting so that, during the very short interval between the breaking of one stick circuit for the relay 63 at the back contact I 03 of the relay 3 and the making of another branch of the stick circuit at the front contact I 95 of the relay 4 the relay 62 will not release its armature, and will thereafter, by closing its make-before-break contacts 95, again energize the relay 63 momentarily and permit it to be stuck up. With the relay 63 thus energized, another operation of the channel circuit selecting relays I l is assured to transmit an indication that the track circuit is unoccupied, the relay 62 being de-energized.

If at the time of the channel circuit selection for the station in question, the train is still on the detector track circuit and the track relay T is still shunted, upon de-energization of the relay 63, as just explained, it remains de-energized until such time thereafter as the track relay T may pick up, whereupon the same energization of the relay 63 occurs, and the same subsequent operation of the channel circuit selecting relays l 4 to transmit an indication that the track circuit has become unoccupied. If it should happen that the track relay '1' at station A (see Fig. 2A) should drop during the short time the relays I -4 are operating, and after the OS channel circuit is broken by the energization of the relay 2 the relay 63 is picked up and stuck up in the same way, and assures a subsequent cycle of operation of the system.

For these reasons, the system, when once set into operation, continues to operate until all new controls or indications have been transmitted. During the transmission of a new control or indication for any given station, all of the other controls or indications for that station are repeated, since all of the individual channel circuits for that station are set up. Thisgives a check on conditions at that station. This checking feature aids greatly in avoiding continued or persistent false indication or control, as may happen in other types of communication systems, such as the code type, where a control or indication is transmitted only once and is not automatically checked until repeated or changed. The dispatcher is able to obtain such check of the conditions at any station by moving any lever for that station over to a different operated position and back again, the relay LV being energized by such lever movement, and causing the channel circuits for that station to be set up, also starting the system into operation, if necessary. If desired, a special key may be provided to enable the operator to energize at will the relays LV for all the stations, so that he is able to check all of the controls and indications, without making a special lever manipulation for each station.

Manual station seZeotin.-Under practical operating conditions, such as in making a non-stop meet, it is often important that the dispatcher should obtain an OS indication of the entranceof a train into certain track sections as quickly as possible, and should also be able to secure prompt operation of a switch or signal in response to a lever movement. Thedispatcher is ordinarily able to determine ahead of time the particular siding, or other control point or zone, where train movements are next likely to occur which would necessitate prompt operation of switches. and signals, since he is kept informed of the train positions by the OS indications, and knows the running time of the trains from point to point.

Although the automatic skipping of stations, as above explained, helps greatly in shorting the total time cycle of operation of the system, and aids in obtaining prompt response to track relay changes or lever operations, there are critical times when the dispatcher is not at all interested for the time being in OS indications from the various points along the track, where trains may enter and leave track sections, and would be assisted in handling the traffic at some congested point, if such unimportant OS indications were discontinued, and the communication system calized, so to speak, to the particular station in which the dispatcher is then interested.

For these reasons, the system of this invention is preferably organized so that the dispatcher may, by a simple manual manipulation, confine the channel circuit selection to some selected station for such period of time as hemay elect. As illustrative of this operation of manual station selection, assume that the dispatcher wishes to confine his attention for a while to station A. To do this, he operates the key K, Fig. 1B, corresponding to station A, and moves either the lever L or the lever LS to a new position and then returns such lever to its former position, which operation is for momentarily closing the pick-up (circuit of the relay LV, as previously described. The movement of the contact finger lfi'l of key K, from the position shown to the other extreme position, establishes a circuit for energizing the relay LV for station A from plus arm 40, wires I58 and I68, fingers I61, wires 233 and 80, relay LV to negative when the selector SS has been operated to select the station A. If the system is at rest, this energization of the relay LV starts it into operation. If the system is running and has passed the station in question, it completes another cycle of operation. In either case, upon coming to station A, the relay CI is energized, since the relay LV for Station A is picked up, and the channel circuits for station A are set up. When the last relay, as 4 is energized, the closing of its front contact 164 does not energize the stepping magnet 36, because the finger l6! of the key K is shifted. Similarly, the stick circuit for relay 4 is not established, and as soon as the negative impulse on the stepping line circuit (which causes energization of the relay 4) ceases, this relay drops, making the bank of relays l-4 ready for another operation. Since the relay LV is held up through the key K, the relay CI is again energized, and the stepping impulses are continued. In order that the relays I -4 at station A, referring to Fig. 2A, may be operated the second time, it is necessary to break the stick circuit for the relay 4 through the contact finger 2l2 of the transfer relay TR which is in its negative or dotted line position, since the system is sectionalized and station A selected. This is done by applying a positive impulse to the transfer line TRL over a circuit from (B+), arm 43 of the shaft 3% in the station A position, wire 234, holding coil 235, finger 236 of key K (now closed), and wire 23'! to the transfer line TEL. This. circuit energizes the transfer relay TR, at the station A, and all of the other relays for other stations nearer the dispatchers 'ofiice, but does not ener gize the transfer relay TR. in the dispatchers office. This causes the contact finger 2l2 of the transfer relay TR at the station selected to move to the right or positive impulse position (these relays for stations near the dispatchers office being already in that position), and break the stick circuit for the relay 4 so that the relays I 3 may be repeatedly operated to set up the channel circuits for that particular station sequentially as long as the key K is operated.

Thus, the dispatcher may select manually any station at which he desires the channel circuits to V be set up continuously, and it is evident that any change in the condition of the track relay at that'station will be practically instantaneously transmitted to the dispatchers oflice, and similarly the signals and the switch at that station respond very quickly upon movement of a lever in the dispatchers office, since all of the channel circuits for one station may be set up in a second or less. Consequently, the dispatcher is able to put himself in direct and practically instantaneous communication with any station he desires, and is able to handle trafiicat that station very expeditiously.

When the dispatcher is through with the station he has selected manually, he restores the key K to the normal position. This sets up the normal operating conditions, so that, when the last 

